QUOTE Is it possible to replace the horrible standard hornby couplings with something more realistic and to decrease the yayning chasm between the carriages?
It is easy or difficult depending on whether or not the couplings are mounted in what are known as NEM "pockets". This is the "easy" option. The pocket design is basically a hollow rectangular section box mounted a set distance from the top of the rail. Couplings which fit this box have a "swallow tail" design which slides into the box. The tips of the swallow tail come out the inner end of the box and spring out to secure the coupling. To remove the coupling you just squeeze the two ends and pull the coupling out. Then you replace the coupling with another design which has a mounting to fit the NEM pocket.
Hornby make a close coupler which will bring your stock closer together. What many people have found is that the remarkably similar Roco close coupler brings the stock even closer and works very well if your curves aren't too tight. Other people swap the couplers for items from Fleischmann. Curiously the Hornby couplings do a great job on Bachmann Mk1 coaches. Bachmann's implementation of the NEM pocket is variable, but they are rather touchy on that subject.
So where do you find these? Almost all new and recent Hornby locomotives, coaches and wagons have NEM pockets. Older stuff has the rather clunky coupling and I'm guessing from your starting post, you've probably got some of these.....
The difficult conversion is hacking off (I mean carefully removing) the offending coupling and replacing it with something more to your taste. You will of course have to decide on what coupling system you want to use. Debates on which is best tend to go on a bit. I don't think we've had one of those debates for a while, but most systems have been covered at some time or other.
I use Kadee myself. This is a US system. It is not unlike a buckeye coupling to look at, but is generally held to be nothing like anything British. I accept that and compensate myself with its operating characteristics which is principally "hands off" shunting.
And now over to someone else to extol the virtues of their favourite.....
David